From: will.deacon@arm•com (Will Deacon)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] arm64: fix missing syscall trace exit
Date: Mon, 8 Jun 2015 11:21:05 +0100 [thread overview]
Message-ID: <20150608102104.GB1654@arm.com> (raw)
In-Reply-To: <1433539683-29539-1-git-send-email-jistone@redhat.com>
Hi Josh,
Thanks for the patch.
On Fri, Jun 05, 2015 at 10:28:03PM +0100, Josh Stone wrote:
> If a syscall is entered without TIF_SYSCALL_TRACE set, then it goes on
> the fast path. It's then possible to have TIF_SYSCALL_TRACE added in
> the middle of the syscall, but ret_fast_syscall doesn't check this flag
> again. This causes a ptrace syscall-exit-stop to be missed.
>
> For instance, from a PTRACE_EVENT_FORK reported during do_fork, the
> tracer might resume with PTRACE_SYSCALL, setting TIF_SYSCALL_TRACE.
> Now the completion of the fork should have a syscall-exit-stop.
>
> Russell King fixed this on arm by re-checking _TIF_SYSCALL_WORK in the
> fast exit path. Do the same on arm64.
>
> v2: Re-enable interrupts before branching to __sys_trace_return.
Please don't include the changelog in the commit message.
> Cc: Catalin Marinas <catalin.marinas@arm•com>
> Cc: Will Deacon <will.deacon@arm•com>
> Cc: Russell King <rmk+kernel@arm•linux.org.uk>
> Signed-off-by: Josh Stone <jistone@redhat•com>
> ---
> arch/arm64/kernel/entry.S | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> index 959fe8733560..988bea43dc74 100644
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@ -608,11 +608,16 @@ ENDPROC(cpu_switch_to)
> */
> ret_fast_syscall:
> disable_irq // disable interrupts
> - ldr x1, [tsk, #TI_FLAGS]
> + ldr x1, [tsk, #TI_FLAGS] // re-check for syscall tracing
> + and x2, x1, #_TIF_SYSCALL_WORK
> + cbnz x2, ret_fast_syscall_trace
> and x2, x1, #_TIF_WORK_MASK
> cbnz x2, fast_work_pending
> enable_step_tsk x1, x2
> kernel_exit 0, ret = 1
> +ret_fast_syscall_trace:
> + enable_irq // enable interrupts
> + b __sys_trace_return
Looks good to me:
Reviewed-by: Will Deacon <will.deacon@arm•com>
I assume this can wait until 4.2?
Will
next prev parent reply other threads:[~2015-06-08 10:21 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-14 19:13 arm syscall fast path can miss a ptrace syscall-exit Josh Stone
2015-05-14 19:35 ` Russell King - ARM Linux
2015-05-14 21:08 ` Josh Stone
2015-05-26 22:38 ` Josh Stone
2015-05-28 10:37 ` Russell King - ARM Linux
2015-05-29 20:13 ` Josh Stone
2015-06-01 10:24 ` Will Deacon
2015-06-03 1:01 ` [PATCH] arm64: fix missing syscall trace exit Josh Stone
2015-06-03 1:11 ` Josh Stone
2015-06-03 9:52 ` Will Deacon
2015-06-03 20:03 ` Josh Stone
2015-06-04 10:06 ` Russell King - ARM Linux
2015-06-04 17:14 ` Josh Stone
2015-06-04 23:17 ` Josh Stone
2015-06-05 15:38 ` Will Deacon
2015-06-05 17:52 ` Tom Lendacky
2015-06-05 21:28 ` Josh Stone
2015-06-08 10:21 ` Will Deacon [this message]
2015-06-08 16:37 ` Josh Stone
2015-06-08 16:43 ` Catalin Marinas
2015-06-23 0:08 ` [PATCH] ARM: enable_irq before ret_fast_syscall tracing Josh Stone
2015-06-23 0:15 ` Josh Stone
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